Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Convertible preferred stock	Common stock	Additional paid-in capital	Accumulated deficit	Accumulated and other comprehensive loss	Total
Balances, Beginning at Dec. 31, 2020	$ 329,983
Balances, Beginning (in shares) at Dec. 31, 2020	223,541,754
Balances, Ending at Mar. 31, 2021	$ 329,983
Balances, Ending (in shares) at Mar. 31, 2021	223,541,754
Balances, Beginning at Dec. 31, 2020		$ 4	$ 58,624	$ (351,676)	$ (190)	$ (293,238)
Balances, Beginning (in shares) at Dec. 31, 2020		360,412
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options			2			2
Exercise of stock options (in shares)		4,862
Employee stock compensation			61			61
Net loss				(8,627)		(8,627)
Cumulative translation adjustment					(4)	(4)
Balances, Ending at Mar. 31, 2021		$ 4	58,687	(360,303)	(194)	(301,806)
Balances, Ending (in shares) at Mar. 31, 2021		365,274
Balances, Beginning at Dec. 31, 2021		$ 204	540,707	(394,754)	(198)	145,959
Balances, Beginning (in shares) at Dec. 31, 2021		20,399,337
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options		$ 1	47			$ 48
Exercise of stock options (in shares)		87,634				87,634
Employee stock compensation			793			$ 793
Net loss				(9,991)		(9,991)
Cumulative translation adjustment					(6)	(6)
Balances, Ending at Mar. 31, 2022		$ 205	$ 541,547	$ (404,745)	$ (204)	$ 136,803
Balances, Ending (in shares) at Mar. 31, 2022		20,486,971